Pulmonary function in wood workers exposed to formaldehyde: a prospective study

Employees exposed to formaldehyde in the woodworking industry (N = 47) and nonexposed control subjects (N = 20) were examined in 1980 by spirometry and the nitrogen washout technique. A transient impairment of lung function was noted over a work shift. Five years later, 21 subjects were still experiencing exposure to formaldehyde. A transient decrease in lung function was again found over a work shift, as evidenced by a reduction in forced mid-expiratory flow (FEF25-75) of 0.15 l/s and an increase in closing volume (CV%) of 3.0% in nonsmokers. Significant decreases in forced expired volume in 1 s as a percent of forced vital capacity (FEV1.0/FVC) and FEF25-75 were also noted over the 5 y in nonsmokers (0.4% and 0.2 l.s/y, respectively, after correction for normal aging). After 4 wk of no exposure (holidays), FEF25-75 and forced expired vital capacity (FVC, FEV1.0) returned to normal in the smoking group. Lung function in smokers improved less during the holiday. A dose-response relationship was found between exposure to formaldehyde and decrease in lung function. Thus, industrial exposure to formaldehyde causes transient lung function impairment over a work shift, with a cumulative effect over the years. The impairment, however, can be reversed with 4 wk of no exposure.